using System;

public class Program

{

    public static void Main()

    {

        int dogCount = int.Parse(Console.ReadLine());

        int otherAnimal = int.Parse(Console.ReadLine());

        double sumDog = dogCount * 2.5;

        int sumOtherAnimal = otherAnimal * 4;

        double totalSum = sumDog + sumOtherAnimal;

        Console.WriteLine("$"{totalSum:f2} lv.");

    }

}